Taste my death ray, 3C321!

By Phil Plait | December 17, 2007 1:51 pm

Black holes are weird. Well, duh, right?

But they do something that surprises most people: besides hoovering down almost everything nearby, they can also eject material as well. And by eject, I mean send it out screaming at nearly the speed of light and heated to a bazillion degrees.

The image above is from the Chandra X-Ray Observatory, and it’s all about this scary scenario. Let’s take a walk down the gravity well, shall we?

Basically, as matter swirls down into the maw of the hole, it forms a flattened disk called an accretion disk. Friction, magnetism, and other forces heat the disk up. A lot. At the poles of the disk, all this heat and force can focus twin beams of fury, jets of matter and energy of unbelievable violence.

Every galaxy has a supermassive black hole in its core, and if these black holes are actively feeding, they can emit these beams. They can be so energetic that these galaxies, called Active Galaxies, are among the brightest objects in the entire Universe!

As you can imagine, it sucks to be in the path of that beam. All that high-energy radiation pelting you, even from thousands of light years away, can be enough to do some serious hurt.

Enter 3C321.

This object is actually two galaxies. Both have active black holes in their cores, but one of the two is creating these death ray beams… and the other galaxy is in the way.

The picture from Chandra shows this drama unfolding. The beams are coming from the lower left, where the more active galaxy sits. The orange and red colors (from Hubble) represent optical and ultraviolet light emitted by the galaxy. This generally indicates regions where stars are being born; it appears as if the beams from the black hole are compressing gas in the galaxy, collapsing it, and aiding it in forming stars.

Purple represents high-energy X-rays (seen by Chandra), caused by all sorts of events, but quite a bit is from the beam slamming into material in the galaxy itself. The blue is lower energy radio emission. Radio waves (detected by MERLIN) are also generated when the beam hits the other galaxy in the upper right. You can see how the beam gets distorted as it rams into the gas in the other galaxy.

The two galaxies are only 20,000 light years apart (for comparison, our Milky Way Galaxy is 100,000 light years across), so the galaxy in the upper right is enduring a world universe of hurt. Any planets in the path of that beam are being pummeled by all manners of radiation. It’s not easy to know if that would make them uninhabitable, but it seems likely; the beams would interact with the air and destroy most of the molecules in the upper atmosphere. Ozone is very susceptible to this, and it’s our ozone layer that protects us from damaging ultraviolet light from the Sun. Without it, the krill and other sea life making up the base of the food chain on our planet would die.

That would be, to use a scientific word, a bummer.

By studying the interaction of the beam from the one galaxy with the other, astronomers can learn just what sorts of things happen when galaxies go bad. And while this seems far removed from our everyday life, I have to add that there is a supermassive black hole in the center of our Galaxy. It’s not currently active, and to be honest there’s no indication that the beams would be aimed at us that even if it were to start chomping down on gas clouds and stars; most likely they would be aimed up and out of the Galaxy, very far from where we are.

Still, forewarned is forearmed. The more we know about this stuff, the better I feel.

Plus, geez, it’s just so cool! Too bad they didn’t release this image before I chose my Top Ten images of the year.

And, finally, I’ll note that I talk about this (as well as black holes in general, and other kinds of killer beams) in "Death from the Skies!" It’ll be a few more months before it’s out, but if you like destruction writ large, you’ll have fun reading the book.


Comments (39)

  1. Chas

    Here’s an idea for a science fiction story:

    An alien solar system is near a black hole emitting high-energy X-rays. A combination of orbital motion and rotation of the black hole will cause the system to pass through the beam in, say 1,000 years. Fine for now, unavoidable death in 1k. What do you do, if you are the political and scientific leaders of that civilization?

  2. fos

    I can’t wait for the book! Great info!

  3. Gnat

    Okay, I don’t mean to sound completely stupid, but I thought that all black holes were active, because they always have a gravitational pull. If this was already discussed, please let me know where I can read more!

  4. HermesThoth

    If these are “active black holes”, what are inactive black holes?

  5. What’s z for this system? Is it far back enough in time that intelligent life might not have evolved there yet? I seem to remember that quasars per se are all in the early universe. The speed-of-light/time-of-event thing…

  6. reasonable

    “Active” black holes are holes which are currently accreting enough material to power their jets. They can’t blast the matter away at near-light speed if there’s nothing there in the first place.
    The hole itself doesn’t do anything different, it’s just that the effects on the surrounding environment are more…let’s say…”Active”

  7. Gnat: “Active” in this context, is one of those special, scientific words (like “theory”) that scientists use differently than everyone else. You might think that pulling stuff in counts as active, but astronomers only consider it active if it’s also shooting stuff out.

    (No fair picking on scientists for their abnormal word usage. Think about a fishermen’s “leader” and a musician’s “staff”, for example.)

  8. Clearly there should be a U.N. resolution denouncing the lower-left body in the 3C321 image (for now designated 3C321-A, “A” for “aggressor”) for its unwarranted and intolerable belligerence against its intergalactic neighbor. The use of galactic-scale active black hole death rays is clearly in violation of multiple international agreements that haven’t been written yet.

    I think a polite but angry letter should be written to let 3C321-A know just how angry we are.

    To Gnat and HermesThoth:

    “Inactive” black holes are black holes that aren’t shooting death beams about. Think about it this way:

    Active black hole: Death ray ACTIVE!
    Inactive black hole: Death ray INACTIVE!

    To Barton Paul Levenson:

    *clicks link* Awww, they’re calling it a “Death Star” Galaxy? What the… If they had to be icky Warsies, they could at least gone with the Galaxy Gun.

    Anyway, websurfing brings up ~1.4 billion LY.

  9. Mankoi

    Wow…where can I learn more about black hole emissions?

  10. Thomas Siefert

    “Say good-bye to all of this… and hello to oblivion. “

  11. Gnat

    Thanks, Guys! I always feel comfortable asking questions on this blog, because I still feel respected…and the “laymen terms” are always helpful!

  12. DrFlimmer

    One more very interesting post, I cannot wait to read the book, too.

    But, when I read your title, I was thinking about Star Wars and the fearful droid C3PO. He would have had a lot of fun and R2D2 would just run straight forward, beeping and screaming, right into the jet! I must watch those old movies again 😉 .

  13. slang

    Black holes don’t just magically attract anything in a galaxy, most matter just orbits around it (or all galaxies would have been ‘sucked up’ already). A black hole acts just like a big amount of mass, you need to be close enough to it to be significantly affected by its gravity.

    Even though supermassive black holes are *big*… space and galaxies are *BIGGER*. At some point there’s just no mass left close enough to the black hole to get sucked in by it, so it goes ‘dormant’.

    Read this bit by BA about our own Sun becoming a black hole (it can’t, it’s not massive enough, it’s just used as an example):

  14. Tod

    Speaking of scientists using words differently, what the heck is “hoovering” as mentioned above in the first sentence?

  15. Phil:
    The National Geographic website credits the NRAO’s VLA with part of the radio data. I’d hate to see the folks at the foot of Mount Jefferson not get their props. Izzis so? Dr. Mark Adams would be the one to contact to check.

  16. Allan Michael

    At 48 years old I remember when evidence of the existence of black holes had been announced and how many thought it was just a bunch of scientists getting a little ahead of themselves. After all, a force in the universe our Universe that consumes everything including light? Rdiculous.
    I’ve been fascinated with black holes since I first heard of them and I’m like a kid in a candy shop in todays world where the science around black holes is growing almost weekly.
    Thank you to Bad Astronomy for weeding out the…..uh……weeds.

  17. GregA


    I suspect he was avoiding the more common nomenclature of “black holes sucking matter” because Black Holes definitely do not suck.

  18. Okay, please don’t laugh me off the site, but I thought that a black hole created such a massively powerful gravitational pull that not even light could escape, hence, black hole.

    I don’t get how something can then be ejected at nearly light speed if light itself cannot escape. Am I obtuse or can someone help me out on this?

  19. pfc

    @Chris – I’ll try to explain with a couple of analogies.

    You’re right that a black hole creates such a strong pull that light can’t escape. But that’s only very, very close to the black hole (about 2 miles for every solar mass.) Farther out, it’s just like a star – matter will orbit around it. Imagine a bunch of slowly moving gas or dust falling in towards the black hole, from all different directions. As it falls closer, it starts to spin, or orbit, faster (like an ice skater pulling in their arms as they spin). At the same time, it starts to flatten in the plane of the orbit and eventually forms a disk. The same thing happens with stars (and the disk goes on to form planets!)

    Now as all this matter falls inwards and spins, it’s being compressed. So the density of the matter increases, and it bangs and rubs against itself and starts to heat up. But most of it is still way too far away to get pulled into the black hole for good – its rotation keeps it from falling in too quickly, but the friction does sap some of its energy so it only slowly spirals into the center.

    So why the jets? I don’t believe the actual physics is that well understood yet, but imagine what happens if you squeeze a wet bar of soap too tightly – it pops out of your hand. This at least shows that a gentle squeeze over a large area (the whole disk) can lead to a small amount of matter being ejected at high speed, perpendicular to the direction of the force. (Of course, for that analogy to work you have to think of your hand and the soap as all being part of the disk.) Just remember that almost all of the matter is way too far away from the black hole to be gobbled up, and the fact that it’s heated up means there’s a lot of energy to be tapped. That’s why black hole accretion disks tend to be visible at high frequencies – UV and X-rays.

    Hope this helps. Any professional scientists feel free to add/correct.

    P.S. “hoovering” = http://www.hoover.com/

  20. Wayne

    Light and matter cannot escape from within the Event Horizon, but the accretion disk and Death Ray jets are outside of this distance. I’m sure someone will write a more detailed answer, but I wanted to get the simple version out there.

  21. Tod

    @pfc: Maybe I’m dense but I don’t get the connection between a vacuum cleaner and a black hole’s gravitational pull. And I must have lived a sheltered life as this is the *first* time I’ve heard that expression. But then I was brought up by a mom who “kirbyed” our carpets. Hoover = suck? Now that’s a stretch. Just as bad as when I underwood my paper essays or palomar the heavens.

  22. Alchemyst

    Both of these black holes are active; absorbing the galaxy around them. In a few 100000 years, these two galaxies could completely join and the black holes could collide.

    What happens when two black holes collide or one “absorbs” the other?

  23. > What happens when two black holes collide or one “absorbs” the other?

    Earth-shattering kaboom.

  24. n9891q

    @Tod –
    Hoover is (was?) the dominant brand of vacuum cleaner in Britain, so that’s what they call vacuum cleaners over there – hoovers that are hoovering up the dirt. Although it seems odd to adopt a brand name like that (please pass me a Kleenex – achoo!), you can find older articles in which such use is cited and Xerox them, but if you get a headache from the dust in the library, you can take a (Bayer) aspirin for relief. Now back to my computer with windows.

  25. Question: if the death ray was actually propagating through a medium through which sound would travel, what noise would it make?


  26. Chris posts:

    [[Okay, please don’t laugh me off the site, but I thought that a black hole created such a massively powerful gravitational pull that not even light could escape, hence, black hole.

    I don’t get how something can then be ejected at nearly light speed if light itself cannot escape. Am I obtuse or can someone help me out on this?]]

    The jet is not coming from inside the black hole. It’s coming from a ring of material falling into the black hole from just outside it. You’re quite correct that material from inside the event horizon can never get out again, unless it’s an alien starship with a faster-than-light drive.

  27. Gary Ansorge

    Look up “synchrotron radiation” in Wikipedia. That should give you a very good insight into the dynamics of black hole radiation. As neutral particles are ripped to shreads by the gravitational “gradient”, they become ionized and are then subject to the rotating magnetic field of the black hole and are accelerated away from the hole at its poles. This is in addition the aforementioned compression effects. There is always a “gradient” near any massive body. It’s the difference between the acceleration experienced by your feet(closer to the center of mass) vs your head.On earth, this is so small as to be(nearly) undetectable, but near a black holes event horizon it becomes humongous and capable of tearing apart individual atoms.

    The inward spiral of two black holes might, at least momentarily, create a “wormhole” in the space between the two, just before they merge but that’s purely theoretical.

    GAry 7

  28. Thanks all, very helpful explanations.

  29. Philippe

    And for a bit of Bad Astronomy…

    Our major local newspaper, La Presse, has an article on this:


    Now, we have 3 major paper in town. One is mostly on political/business/economy subjects(Le Devoir), the second deals with the famous people, the hockey games and assorted petty crimes (Le Journal de Montreal.

    And then there’s La Presse. Which is supposed to be a good paper. Has a science section once a week, etc. I would expect them to threat this properly. But sadly, they close off with this :

    “…les deux galaxies en question sont très proches, éloignées de 20 000 années lumière seulement, soit la même distance qui sépare la Terre de la Voie Lactée, note la Nasa.”

    Let me translate for you all: “…those two galaxies are quite close, only 20 000 light-years apart, which is the same distance between planet Earth and the Milky Way, according to Nasa.”

    Sorry about the crappy translation, but you get the idea. I’d like to see the “raw” Nasa press release to see why somebody could mis-interpret it so badly.

    Apparently, we are doomed too…

  30. Gary:

    You’re taking me too seriously. I still vote for “Earth-shattering kaboom.”

  31. Michael Lonergan

    So, that’s where Saddam hid his weapons of mass destruction.

  32. tadpole

    I have heard that certain galaxies do in fact make a noise, although it may not be a “kaboom”, more like a sonor sort of sound. How true is that?

  33. tim

    …Kinda looks like that planet eating thing in that one Star Trek adventure…..

  34. OK, let’s clear some air here.

    First “Active” is not being redefined by science as asserted above. Active means the process is ongoing. A sailboatd’s sail is active, but there must be wind. The black hole needs to have a stream of matter falling in to power the beam effect.

    Second, we are looking at one frame of a moving picture. These galaxies have been colliding for millions of years and the tidal forces are causing many clusters and possibly whole spiral arms to fall into the grational well.

    Imagine the well known high speed film of the bullet hitting the apple. One frame may show the bullet at one moment in the stream of moments and that photo would show the apple’s first splash as the bullet strikes.

    The composite photo shows several causes, and effects.
    * Gravity is disrupting both galaxies.
    * Spiral arms are being severly distorted.
    * Many clusters will be lost to the depths of space.
    * Many more clusters will be swallowed.

    Ultimately, both black holes will capture each other and ultimately the pair will consume the remaining stars, nebulas and dust in the general area, except for the outermost clusters with high radial velocities which are destined to escape.

    The “sound” of a galaxy would be the frequencies at which it resonates. A flute or a piano string vibrates, that vibration is its sound. Objects tend to have frequencies that reinforce energy movement, and other frequencies at which energy is dampened or absorbed. A gravitationally connected web of rotating particles would tend to produce all frequencies, like an irregular galaxy or a supercluster.

    A spiral would have positive reinforcements at a whole number ration as dictated by the number of arms, assuming the arms are roughly the same size. Thus, that galaxy would have a dominant note corresponding to this frequency, on the order of thousands of years per cycle.

    Since there are no physical connections between solar masses the effect would be very subtle and it would take millions of years for standing waves to be created by the millions of gravitional vortices.

    If the galaxy is spinning in a circle and not pulled by an outside disruptive force the arms should even out and form a barred spiral with the bar’s size relative to the vibrational frequncy of the galaxy.

    It it possible that two galaxies of the same size and orientation, in close proximity, might actually cross gravity waves harmoniously and actually affect each other, a cosmic tuning up perhaps.

    Well, keep on thinking!

    We need more critical thinkers… especially at voting time!

    John Rosengarten, Chicago USA


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